The present invention relates to a door lock for motor vehicles having a control element which is driven by an electric motor, is controlled by an electronic control unit and can be moved, upon a control signal emitted by a transmitter, into a position which at least prepares the opening of the door lock.
Door locks of this general type are known. The transmitter, which is also called a "radio key", as a rule, supplies a signal which is transmitted in a wireless manner by the signal receiver to the electronic control system and operates, for example, on the basis of electromagnetic waves. When the elect:conic control system receives a corresponding signal from a pertaining radio key, the control element can unlock the door lock or move it into a predetent position from which the door lock can then be opened, for example, by means of the conventional door handle.
Door locks of this type are very user friendly. However, as a rule, they have a specific disadvantage. Their method of operation is a function of the operability of the wiring by which the control element or the electronic control system is supplied with energy. In the case of an accident or in the case of a defect of the wiring, however, a condition may occur in which the proper functioning of the electronic control system or of the control element is no longer ensured. Although it is known in this connection to provide a mechanical emergency measure for such a case, in which the door lock can be unlocked purely mechanically without any electrical or electromagnetic remedial measures, considerable mechanical expenditures must be provided in this case which cancel the advantage gained in user friendliness in such a lock by the costs, the weight and also to the operability.
It is an object of the invention to provide a door lock of the initially mentioned type which retains the mentioned advantages with low additional expenditures and which is also operable as required or in a case of emergency.
This and other objects are achieved by the present invention which provides a door lock for motor vehicles comprising a control element which is drivable by an electric motor, an electronic control system coupled to the control element to control the control element, the control element being movable into a position which at least prepares the opening of the door lock in response to a control signal, and an energy accumulator assigned to the electronic control system and is independent of wiring of the motor vehicle, the energy accumulator being connectable to the signal receiver if required such that the signal receiver will activate the control element directly.
By the provision of the self-sufficient energy accumulator, it becomes possible to operate the control element in the event of a failure of the wiring or of the electronic control system. As a rule, operability is also ensured in the event of an accident because the connecting paths between the energy accumulator, the signal receiver and the control element may be designed to be short, and the risk of damage to the unit comprising these three elements can therefore be reduced considerably. On the other hand, the characteristic of not connecting the energy accumulator to the signal receiver before it is required, provides that under normal operating conditions, i.e., when the wiring is operable, the energy accumulator is not used and is therefore available to an unlimited degree when it is required.
Certain embodiments of the invention permit an even more pronounced independence of the unit comprising the energy accumulator, the control element and the signal receiver from the condition of the wiring, because the condition in which the energy supply by the wiring no longer meets a minimum requirement is recognized by the signal receiver itself such as through an energy level detector 20 and, as a rule, the energy accumulator is activated automatically. The alternative case, in which the signal receiver can be manually connected to the energy accumulator, as a rule, requires higher expenditures because the minimum requirement must then, for example, be determined by the electronic control system in that the control element is not operable.
In certain embodiments of the invention, the energy accumulator is activatable by a switch coupled with the door handle, thereby providing a simple possibility of activating the energy accumulator as required. In this case, it is a special advantage that the failure of the wiring does not become noticeable to the user in a particularly negative manner, and the activating of the energy accumulator takes place in a manner that is self-evident and virtually "natural" for the user of the vehicle. After emitting an opening signal by means of the radio key, the user will attempt to unlock the door lock as usual. If the wiring is incapable of serving the control element, the vehicle user can, as a rule, recognize the sequence interference. He will then attempt to open the door in the customary manner by means of the door handle. This activates the energy accumulator. The door lock can then be unlocked by the vehicle user. He may, for example, again trigger an opening signal by means of the radio key and thus move by means of the signal receiver, the control element into the opening direction. Naturally, it is also possible to mechanically open the door lock so long as a mechanical connection is provided between the door handle and the door lock by way of the control element activated by the signal receiver and the energy accumulator.
A complement or an alternative to a self-sufficient energy accumulator is provided by certain embodiments that include an energy accumulator which can be moved by means of the door handle, for example, in the manner of a dynamo. As in the case of a static energy accumulator, also in this case, the energy generator may be capable of being activated only when required.
Certain embodiments provide a possibility for utilizing the energy accumulator for at least one other door lock. For this purpose, an electrical connection need only be provided between the energy accumulator, the pertaining signal receiver and the control element of the second door lock. By means of an energy accumulator, it is therefore possible to electrically open at least two doors independently of the other wiring.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.